GROWTH IN PINNIPEDS

Various renal functions were studied in the Baikal seal (Pusa sibirica), which inhabits freshwater, and in the ringed seal (P. hispida), its marine counterpart. The urine osmolality progressively increased during dehydration (and fasting), reaching a plateau after 35 h. The average maximum urine osmolality was 2,374±60 and 2,052 ± 100 mOsm/kg in the Baikal and ringed seals, respectively. Urea and electrolytes (Na, K, and Cl) accounted for 82.6% and 9.3%, respectively, of total urine osmolality in the Baikal seal, and for 72.6% and 16.1%, respectively, in the ringed seal. Administration of 500 ml 0.15 M NaCl solution (stomach tubing) during fasting had little effect on the level of urine osmolality; however, the contribution of urea to total urine osmolality decreased (to 60%) while that of electrolytes increased (to 23%). Using the endogenous creatinine clearance as a measure of glomerular filtration rate, it was estimated that about 0.2% of filtered water and 0.05% of filtered Na are excreted during dehydration. There was a significant positive correlation between urine osmolality and urinary excretion of ADH during the 70-h dehydration period; however, there was no significant correlation between urinary Na and aldosterone excretions. Administration of 1 liter water (stomach tubing) resulted in a marked diuresis accompanied by a reduction in urine osmolality. In one seal, a hypotonic urine was obtained. This diuretic response was not accompanied by a parallel change in creatinine clearance, but by a moderate increase in the excretion of solutes. Administration of 500 ml 0.5M NaCl solution (i.v.) resulted in a rapid increase in the excretion of water and Na. The Na (and Cl) concentration of urine increased to 350-500 mEq/1, while that of urea decreased to 800 mM/1. The percentage of excretion of filtered Na also increased to about 2.0. There were no major differences in renal functions between the Baikal and ringed seals. Moreover, the present results are qualitatively similar to those obtained from the harbor seal by previous investigators. It is concluded that the Baikal seal, isolated from seawater and living in freshwater for .5 million years, remarkably retained the renal function they possessed at the time of isolation.

28 - Morphometric comparison of skulls of seals of the subgenus Pusa

The allelic diversity of exon 2 (DQB gene) and exon 3 (DRB gene) of major histocompatibility complex class II was studied for the first time in two species of the landlocked pinnipeds, Baikal (N = 79) and Caspian (N = 32) seals, and these were compared with the widespread Arctic species, the ringed seal (N = 13). The analysis of the second exon comprising the antigen-binding region revealed high allelic diversity in all three species, but the pattern of the diversity was the most specific for the Baikal seal. This species differs from the other two by the smallest number of alleles in the population, yet they have the largest number of alleles per individual and by the maximum similarity of individual genotypes. Presumably, this specificity is a consequence of the spatial and temporal homogeneity of the Lake Baikal environment. Analysis of the third exon encoding the conserved β2-domain showed that the Baikal seal differs by the greatest number of amino acid sequences per individual, while the Caspian seal has the lowest number of variants. A single variant of the β2-domain, the same as in the ringed seal, predominates in the Caspian seal, whereas in the Baikal seal the two other variants predominate. At the same time, three species-specific amino acid sequences were observed among minor variants in the Caspian seal, while only one was found in the Baikal seal. This fact may suggest a longer period of independent evolution in the Caspian seal compared to the Baikal seal.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 305:261-274 (2005) - doi:10.3354/meps305261 Fatty acid composition of blubber of the Baikal seal Phoca sibirica and its marine relative, the ringed seal P. hispida Otto Grahl-Nielsen1,*, Ann-Kristin Halvorsen1, Nikolai Bodoev2,3, Lena Averina2, Larisa Radnaeva2,3, Nikolai Pronin4, Reijo Käkelä5, Eygenii Petrov6 1Department of Chemistry, University of Bergen, 5007 Bergen, Norway2Baikal Institute of Natural Management SB RAS, 630033 Ulan-Ude, Russia3Buryat State University, 630000 Ulan-Ude, Russia4Institute of General and Experimental Biology SB RAS, 630033 Ulan-Ude, Russia5Department of Biology, University of Joensuu, 80101, Finland6East Siberian Fish Centre, 630000 Ulan-Ude, Russia *Email: otto.grahl-nielsen@kj.uib.no ABSTRACT: The fatty acid (FA) composition was determined in the blubber of 5 adult Baikal seals Phoca sibirica caught in July 2001, nine 1-mo old pups caught in April 2002, and 25 adults and fetuses from 3 of these, caught in October 2002, all along the SE shores of Lake Baikal, eastern Siberia. For comparison, FA in the blubber of ringed seals P. hispida, the closest marine relative of the Baikal seal, caught along the ice edge around Svalbard during 1999 and 2000 were also analyzed. The FA of the main prey of the Baikal and ringed seals, the endemic golomyanka Comephorus baikalensis and polar cod Boreogadus saida, respectively, were also studied. The same suite of FA was found in all samples. Saturated FA (SFA) with branched chains, all n6 polyunsaturated FA (PUFA) and 18:3n3 and 20:3n3 were more abundant in the blubber of the Lake Baikal seal and in the golomyanka than in the blubber of the marine ringed seal and marine fishes. In contrast, the relative levels of monounsaturated FAs (MUFA) with 20 and 22 carbons and polyunsaturated 20:5n3 were lower in the Baikal species than in the Svalbard species. The FA composition of the inner blubber was significantly different from the FA composition of the outer blubber in both species. Despite large differences in FA composition between Baikal and ringed seal blubbers, vertical differences were manifested in the same FA: MUFA with 14, 16 and 18 carbons were present in higher relative abundance in the outer than in the inner layer. In both species all the other quantitatively important FA had lower or equal relative values in the outer layer. The FA composition of the seals' blubber differed from that of their main prey. The difference was, however, smaller between prey and inner blubber than between prey and outer blubber. The FA composition of the inner blubber of adults showed temporal differences. Since the change from prey to blubber in relative concentration occurred in the same direction for all but 5 FA, the selection of FA during deposition in the inner blubber was similar for the 2 species, even though there was a large difference between the general FA composition of the freshwater and marine lipids. The FA composition in the blubber of adults, pups and fetuses differed. KEY WORDS: Baikal seal · Ringed seal · Blubber stratification · Fatty acid composition · Prey · Endogenous factors Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 305. Online publication date: December 23, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.

Generation of induced pluripotent stem (iPS) cells expanded possibilities of pluripotency and early development studies. Generation of order Carnivora iPS cells from dog (Canis lupus familiaris), snow leopard (Panthera uncia), and American mink (Neovison vison) was previously reported. The aim of the current study was to examine conditions of pinniped fbroblast reprogramming. Pinnipeds are representatives of the suborder Caniformia sharing conservative genomes. There are several ways to deliver reprogramming transcription factors: RNA, proteins, plasmids, viral vectors etc. The most effective delivery systems for mouse and human cells are based on viral vectors. We compared a lentiviral vector which integrates into the genome and a Sendai virus­based vector, CytoTune EmGFP Sendai Fluorescence Reporter. The main advantage of Sendai virus­based vectors is that they do not integrate into the genome. We performed delivery of genetic constructions carrying fluorescent proteins to fbroblasts of seven Pinnipeds: northern fur seal (Callorhinus ursinus), Steller sea lion (Eumetopias jubatus), walrus (Odobenus rosmarus), bearded seal (Erignathus barbatus), Baikal seal (Pusa sibirica), ringed seal (Phoca hispida), and spotted seal (Phoca largha). We also transduced American mink (N. vison), human (Homo sapiens), and mouse (Mus musculus) fbroblasts as a control. We showed that the Sendai virus­based transduction system provides transgene expression one­two orders of magnitude higher than the lentiviral system at a comparable multiplicity of infection. Also, transgene expression after Sendai virus­based transduction is quite stable and changes only slightly at day four compared to day two. These data allow us to suggest that Sendai virus­based vectors are preferable for generation of Pinniped iPS cells.

In recent years, there has been an increase in infectious diseases in marine mammals, including brucellosis, infections of morbillivirus, herpesvirus, and poxvirus. Several serological diagnostic methods, including enzyme-linked immunosorbent assays, immunofluorescence assays (ELISA), and western blotting, have been used to detect antibodies against pathogens in marine mammals. However, options for commercial secondary antibodies used to detect antibodies in marine mammals are limited; therefore, the use of proteins A, G, or chimeric protein AG may provide a suitable alternative. This study aimed to assess the use of proteins A, G, and chimeric protein AG to detect marine mammal immunoglobulins. Currently, there are no comparative studies on the use of proteins A, G, and chimeric protein AG for the detection of immunoglobulins in marine mammals. In this study, we used ten pinnipeds’ species (Baikal seal, California sea lion, harbor seal, northern fur seal, ringed seal, South American fur seal, South American sea lion, spotted seal, Steller sea lion, and walrus) and five cetacean species (beluga whale, bottlenose dolphin, harbor porpoise, killer whale, and Pacific white-sided dolphin) and compare binding ability to proteins A, G, or chimeric protein AG by ELISA. The results revealed that the immunoglobulins from pinniped and cetacean species reacted more strongly to protein A than protein G. In addition, the immunoglobulins of pinnipeds and cetaceans showed a strong binding ability to chimeric protein AG. These results suggest that proteins A, G, and chimeric protein AG would be used to help further develop serological assays.

Phocid seals exhibit a range of body sizes and life-history traits. They forage at a wide range of spatial scales from long-distance oceanic movements (e.g., northern elephant seals) to short local trips of resident coastal species (e.g., harbor seals). Our current understanding of the foraging behavior of phocids comes mainly from northern and southern elephant seals, gray seals, harbor seals, ringed seals, and Hawaiian monk seals. Foraging tactics appear to develop rapidly within the first year of life, but the effect of age on the foraging of older animals appears to be weak. Sex differences in seasonal foraging distribution and diving behavior are evident in several dimorphic species but less evident or absent otherwise. Body size, condition, and reproductive status also influence foraging trip characteristics and dive effort. Recent studies reveal the consequences of foraging on mass gain and reproductive success and how those consequences vary with interannual and longer-term environmental change. More accurate location tags, improved dataloggers, and new analysis tools are being used to measure and infer in-situ patterns of foraging behavior and foraging success. Animal-borne instruments can also collect data on the ocean environment, which have proven useful in describing foraging behavior.KeywordsPhocidsIntrinsic and environmental driversMovementDivingForaging successLife-history consequencesNew toolsAnalysis methods

Pinnipedia karyotype evolution was studied here using human, domestic dog, and stone marten whole-chromosome painting probes to obtain comparative chromosome maps among species of Odobenidae (Odobenus rosmarus), Phocidae (Phoca vitulina, Phoca largha, Phoca hispida, Pusa sibirica, Erignathus barbatus), and Otariidae (Eumetopias jubatus, Callorhinus ursinus, Phocarctos hookeri, and Arctocephalus forsteri). Structural and functional chromosomal features were assessed with telomere repeat and ribosomal-DNA probes and by CBG (C-bands revealed by barium hydroxide treatment followed by Giemsa staining) and CDAG (Chromomycin A3-DAPI after G-banding) methods. We demonstrated diversity of heterochromatin among pinniped karyotypes in terms of localization, size, and nucleotide composition. For the first time, an intrachromosomal rearrangement common for Otariidae and Odobenidae was revealed. We postulate that the order of evolutionarily conserved segments in the analyzed pinnipeds is the same as the order proposed for the ancestral Carnivora karyotype (2n = 38). The evolution of conserved genomes of pinnipeds has been accompanied by few fusion events (less than one rearrangement per 10 million years) and by novel intrachromosomal changes including the emergence of new centromeres and pericentric inversion/centromere repositioning. The observed interspecific diversity of pinniped karyotypes driven by constitutive heterochromatin variation likely has played an important role in karyotype evolution of pinnipeds, thereby contributing to the differences of pinnipeds’ chromosome sets.

Climate change is causing a decrease in Arctic sea ice extent and thickness, leading to alterations in interspecific interactions, food availability, and contaminant exposure for marine organisms, including higher trophic level predators such as ringed seals (Pusa hispida, natsiq) and bearded seals (Erignathus barbatus, ujjuk) who forage in disparate habitats. Despite rapid Arctic ecosystem change, spatiotemporal variability in the foraging behavior and contaminant dynamics of these Arctic seals remains poorly understood. Using stable isotopes (δ13C, δ15N, δ34S) and total mercury (THg) concentrations in claw annuli, we investigated spatiotemporal variability in the foraging ecology and contaminant exposure of ringed and bearded seals in relation to environmental factors at the individual, species, and between-species levels across a latitudinal gradient in the eastern Canadian Arctic. Overall, ringed seals fed more pelagically and had higher THg levels than bearded seals. A latitudinal gradient emerged where seals at lower latitudes had lower δ15N and THg, and foraged more pelagically than seals at higher latitudes. Bearded seals, and seals at lower latitudes, had higher degrees of individual specialization calculated using individual and population isotope variance analysis, suggesting they are more vulnerable to rapid environmental changes than ringed seals and seals at higher latitudes. Additionally, seals consumed relatively more pelagic prey in years with longer open water periods, supporting evidence of climate-induced shifts in Arctic marine mammal foraging strategies towards pelagic prey. This study provided insight into spatial variation in foraging strategies, habitat use, and contaminant exposure of two Arctic marine predators; information which can be used to inform species management and conservation efforts.

We expected that the enlarged area of zygomatic arch, one of some skull characters adapted for enlarged eye, has an influence on form and function of muscles of mastication in the Baikal seal (Phoca sibirica). So, in this species, the Mm, masseter, temporalis, pterygoidei, digastricus were observed in the macroscopic level. The skull characters related to these muscles were also compared between the Baikal seal and a close-related species, the ringed seal (Phoca hispida). The Mm, masseter and temporalis were well-developed using the enlarged attachment area of zygomatic arch. In contrast, the M. digastricus is suggested to be not so important in the Baikal seal, because the temporal bone is not so developed as in the ringed seal. It is suggested that the Baikal seal has especially developed the Mm. temporalis and masseter using an enlarged area of zygomatic arch among Pusa species. We also suggest that the robust temporal bone is equipped to have the M. digastricus developed as a main retractor of mandibular body in the ringed seal.

Genetic diversity of neutral markers (15 microsatellite loci) was assessed for the first time in two landlocked seal species, the Baikal seal Pusa sibirica and Caspian seal P. caspica, and compared with that in the oceanic species ringed seal P. hispida of the same genus. Lower genetic diversity was observed in both of the landlocked seal species, the Baikal seal having the lowest level. A high probability of a historical bottleneck effect was shown for both Baikal and Caspian seals, while signs of a sharp decline in the past were not observed in the ringed seal population. A data analysis with the VarEff package suggested different times to the most recent common ancestor (TMRCA) for each of the three populations. The time established for the Baikal seal was significantly shorter than that of the Caspian seal.

Sea lion and seal populations in Alaskan waters underwent various degrees of decline during the latter half of the twentieth century and the cause(s) for the declines remain uncertain. The stable carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) isotope ratios in bone collagen from wild Steller sea lions (Eumetopias jubatus), northern fur seals (Callorhinus ursinus) and harbor seals (Phoca vitulina) from the Bering Sea and Gulf of Alaska were measured for the period 1951-1997 to test the hypothesis that a change in trophic level may have occurred during this interval and contributed to the population declines. A significant change in δ(15)N in pinniped tissues over time would imply a marked change in trophic level. No significant change in bone collagen δ(15)N was found for any of the three species during the past 47years in either the Bering Sea or the Gulf of Alaska. However, the (15)N in the Steller sea lion collagen was significantly higher than both northern fur seals and harbor seals. A significant decline in δ(13)C (almost 2 ‰ over the 47years) was evident in Steller sea lions, while a declining trend, though not significant, was evident in harbor seals and northern fur seals. Changes in foraging location, in combination with a trophic shift, may offer one possible explanation. Nevertheless, a decrease in δ(13)C over time with no accompanying change in δ(15)N suggests an environmental change affecting the base of the foodweb rather than a trophic level change due to prey switching. A decline in the seasonal primary production in the region, possibly resulting from decreased phytoplankton growth rates, would exhibit itself as a decline in δ(13)C. Declining production could be an indication of a reduced carrying capacity in the North Pacific Ocean. Sufficient quantities of optimal prey species may have fallen below threshold sustaining densities for these pinnipeds, particularly for yearlings and subadults who have not yet developed adequate foraging skills.

Karyotypes of the harbor seal, Phoca vitulina (2N = 32), the bearded seal, Erignathus barbatus (2N = 34), the Weddell seal, Leptonychotes weddelli (2N = 34), the walrus, Odobenus rosmarus (2N = 32), the Steller sea lion, Eumetopias jubata (2N = 36), and the northern fur seal, Callorhinus ursinus (2N = 36), are described and compared with those of the ringed seal, Pusa hispida, and California sea lion, Zalophus californianus, reported by other workers. These are discussed with reference to current theories of pinniped phylogeny and systematics. The number and morphology of chromosomes in these eight species, representing each family and subfamily of pinnipeds, were found to be remarkably similar. This is interpreted as evidence of close interrelationship, commensurate with the theory of monophyletic origin. Karyograms of the harbor seal and ringed seal are virtually identical, as are those of the bearded and Weddell seals and those of the Steller and California sea lions. The karyotype of the fur seal is similar to the sea lions', while that of the walrus resembles the phocids' in some ways and the otariids' in others. A need for thorough comparative studies and reappraisal of pinniped systematics at the subfamilial and generic levels is indicated.

Feeding performance studies can address questions relevant to feeding ecology and evolution. Our current understanding of feeding mechanisms for aquatic mammals is poor. Therefore, we characterized the feeding kinematics and performance of five Steller sea lions (Eumetopias jubatus) and six northern fur seals (Callorhinus ursinus). We tested the hypotheses that both species use suction as their primary feeding mode, and that rapid jaw opening was related to suction generation. Steller sea lions used suction as their primary feeding mode, but also used a biting feeding mode. In contrast, northern fur seals only used a biting feeding mode. Kinematic profiles of Steller sea lions were all indicative of suction feeding (i.e. a small gape, small gape angle, large depression of the hyolingual apparatus and lip pursing). However, jaw opening as measured by gape angle opening velocity (GAOV) was relatively slow in Steller sea lions. In contrast to Steller sea lions, the GAOV of northern fur seals was extremely fast, but their kinematic profiles indicated a biting feeding mode (i.e. northern fur seals exhibited a greater gape, a greater gape angle and minimal depression of the hyolingual apparatus compared with Steller sea lions). Steller sea lions produced both subambient and suprambient pressures at 45 kPa. In contrast, northern fur seals produced no detectable pressure measurements. Steller sea lions have a broader feeding repertoire than northern fur seals, which likely enables them to feed on a greater variety of prey, in more diverse habitats. Based on the basal phylogenetic position of northern fur seals, craniodental morphological data of the Callorhinus lineage, and the performance data provided in this study, we suggest that northern fur seals may be exhibiting their ancestral feeding mode.

Antibodies to influenza A virus were detected using enzyme-linked immunosorbent assay (ELISA) in the sera from two of seven Baikal seals (Phoca sibrica) and from five of six ringed seals (Phoca hispida) in Russia. In a hemagglutination-inhibition test using H1-H15 reference influenza A viruses, ELISA-positive sera from one Baikal seal and four ringed seals reacted to A/Aichi/2/68 (H3N2) and A/Bangkok/1/79 (H3N2) strains. One ringed seal serum sample reacted to A/seal/Massachusetts/1/80 (H7N7). The present results suggested that human-related H3 viruses were prevalent in Baikal seals and ringed seals inhabiting the central Russian Arctic.